[wireties]

Our team is in its 11th year (I think). We've used swerve for 2 years, mecanum for 3 years and tank drive the other years.

Our mecanum was very well done, almost as well as it can be done w/o adding locking wheels or brakes of some kind. We had no trouble with the average tank drive opponent in qualifying matches. We just spun off them or juked them - often it was embarrassing. But late in eliminations rounds tank drive robots with good drivers assigned to specifically stop us could really slow us down. But we stuck with mecanum for a goofy reason I reckon, the students loved to drive the thing. It is a lot of fun.

Our swerve drive worked pretty well the first year (lunacy) but not so well the next. We had some steering problems but it was a design issue (windows motors, not enough torque etc). We fixed it eventually. We loved swerve also - it is also fun to drive. But swerve involves a lot of relatively complex machining. I disagree that the software is complex - the math is pretty straight forward. We stopped doing swerve because one of our mentors (and the best machinist) got sick the next year.

For the last several years we've tried chain and belt driven single and two-speed tank drives. They work well and are relatively simple to design and build. It takes us a single afternoon to hammer out the design. It is very strong and reliable (except for changing out the occasional chain or belt).

So what advice can I give you? Do NOT try swerve w/o a foolproof off-season design working. You could kill a build season schedule (for most teams). If you have a good swerve you will be more maneuvrable than a tank drive. Is it worth the weight and complexity? ... depends on the game. A properly geared two-speed 6-motor tank will still push you around a little (not like a mecanum though) because you will probably be limited to 4 motors and a single gear.

Finally persons on CD and in competitions are too hard on mecanum drives. They can be better than most people think. And as Ether points out (in dozens of other threads) the mathematics and operation behind mecanum is almost universally misunderstood. For example ours could park on a bridge (but not push someone else up the bridge), fly over bumps and play passable defense against tanks (if we caught them on the corner and spun them around rather than push them). But the prejudice against mecanum is not w/o some basis and there are MANY teams that will NEVER pick a mecanum alliance partner.

HTH